A NORTH Korean defector has warned the West that Kim Jong-un could launch a devastating nuclear attack as they bolster their submarine fleet.

A North Korean defector has said the West should not rule out the possibility of a preemptive strike

Defector Kim Heung-kwang revealed the North is developing a gigantic 2,700 tonne submarine built from parts purchased from Russian vessels.

Mr Heung-kwang said: "The decision for this development was made by Kim Jong-un and his advisors, who wanted to create an environment in which the US and international society can’t easily underestimate the North’s preemptive nuclear strike capability.”